Polymer compositions for injection stretch blow molded articles

ABSTRACT

A polymer composition of polypropylene copolymer and 1 to 50% by weight of hard resin. The polypropylene copolymer is either an impact copolymer or a random copolymer. The polymer composition can be used to make injection stretch blow molded articles having improved top load strength.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 13/075,208, filed Mar. 30, 2011, which is incorporated hereinby reference in its entirety for all purposes.

FIELD

The present invention generally relates to polymer compositions. Morespecifically the present invention relates to polypropylene basedpolymer compositions for injection stretch blow molding (ISBM) ofarticles, and methods of making and using same.

BACKGROUND

Injection stretch blow molding (ISBM) is a process for producing hollowplastic forms, such as bottles and dairy and juice containers.Manufacturers continue to search for alternative polymers and methods ofpreparing these products.

Various polymer compositions of polypropylene can be used to produceISBM articles. Depending on the polymer compositions, these articles canvary greatly in both mechanical and optical properties, such as top loadstrength, drop impact strength, haze, and opacity, as well asprocessability.

It is desirable to improve mechanical, optical, and processabilityproperties of polymer compositions used to make commercial products. Itis toward this end that the present invention is directed, particularlyin the production of ISBM articles.

SUMMARY

The present invention, in its embodiments, concerns a polymercomposition that includes a polypropylene copolymer component and a hardresin component. Generally, the polymer composition includes apolypropylene copolymer and 1 to 50% by weight of a hard resin. Thepolymer composition can be useful for injection stretch blow moldingapplications.

In one embodiment, either by itself or in combination with otherembodiments, the present invention is a polymer composition thatincludes a polypropylene impact copolymer and a hard resin. Thepolypropylene impact copolymer can include at least 60% by weight of apolypropylene homopolymer and less than 40% by weight of apropylene-ethylene rubber. The polypropylene impact copolymer can have amelt flow rate of from 1 to 500 g/10 min. The addition of hard resin cancause an injection stretch blow molded bottle to have at least 20%better top load strength, as compared to neat impact copolymer. Theinjection stretch blow molded bottle made from the composition can havea normalized top load strength calculated by the top load strengthdivided by bottle weight of at least 5.5 N/g.

In one embodiment, either by itself or in combination with otherembodiments, the present invention is a polymer composition thatincludes a polypropylene random copolymer and a hard resin. Thepolypropylene random copolymer can have less than 10% by weight ofethylene comonomer. An injection stretch blow molded bottle made fromthe composition can have a normalized top load strength calculated bythe top load strength divided by bottle weight of at least 6.5 N/g.

In one embodiment, either by itself or in combination with otherembodiments, the present invention is a method for making a polymercomposition that includes providing a polypropylene copolymer,mechanically blending the polypropylene copolymer with 1 to 50% byweight of a hard resin, and extruding the polypropylene copolymer andthe hard resin to form a substantially homogenous polymer blend, wherethe polymer blend consists essentially of the polypropylene copolymerand the hard resin. Embodiments of the polypropylene copolymer can beeither an impact copolymer or a random copolymer or combinationsthereof.

In one embodiment, either by itself or in combination with otherembodiments, the present invention is an injection stretch blow moldedarticle made from a polymer composition that includes a polypropyleneimpact copolymer and 1 to 50% by weight of a hard resin. The article canhave a top load strength of from 130 to 160 N, an 80 to 100% pass ratefor a drop impact test (from 6 feet at 40° F.), and optical propertiesof haze from 60 to 80% and gloss)(45° from 5 to 15.

In one embodiment, either by itself or in combination with otherembodiments, the present invention is a method of making an injectionstretch blow molded article by providing a polymer composition thatincludes a polypropylene impact copolymer and 5 to 50% by weight of hardresin, injection molding the polymer composition into a preform and thenstretch-blowing the preform into an article. The article can be used inlow temperature applications, such as at or below 40° F. The article canbe either opaque or semi-opaque.

The various aspects of the present invention can be joined incombination with other embodiments of the invention and the listedembodiments herein are not meant to limit the invention. Allcombinations of embodiments of the invention are enabled, even if notgiven in a particular example herein.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a chart showing the top load strength in N for bottles madefrom polymer compositions of polypropylene random copolymer and hardresin.

FIG. 2 is a chart showing gloss (45°) for bottles made from polymercompositions of polypropylene random copolymer and hard resin.

FIG. 3 is a chart showing haze (%) for bottles made from polymercompositions of polypropylene random copolymer and hard resin.

DETAILED DESCRIPTION

The present invention is for a polymer composition that includes apolypropylene copolymer and hard resin. The polypropylene copolymer canbe an impact copolymer (ICP) or a random copolymer (RCP), orcombinations thereof.

In one embodiment, the polypropylene copolymer is an impact copolymer(or ICP). Impact copolymers may also be referred to as heterophasiccopolymers. An impact copolymer generally includes a rubbery phase ofcomonomer dispersed within a matrix phase. The matrix is a generallyhard plastic, which alone can suffer poor impact absorption at lowtemperatures. The rubbery phase can decrease the hardness of the polymercomposition while increasing impact absorption. In some cases, theinclusion of a rubbery phase can also decrease optical clarity andincrease haze. However, certain articles used at low temperatures arealso articles which are either not affected by or are benefited byincreased opacity. Dairy products, for instance, store better incontainers of higher opacity with reduced light penetration.

The matrix phase of the impact copolymer can include a polypropylenepolymer, for instance, a polypropylene homopolymer. The homopolymer maycontain up to about 5 wt % of another alpha-olefin, including but notlimited to, C₂ and C₄ through C₈ alpha-olefins, such as 1-butene andethylene. Despite the potential presence of small amounts of otheralpha-olefins, this polymer is generally referred to as a polypropylenehomopolymer.

The rubbery phase of the impact copolymer includes comonomers selectedfrom the group consisting of C₂ to C₂₀ alkenes. For example, thecomonomers may be selected from ethylene, propylene, 1-butene,1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene,4-methyl-1-pentene and combinations thereof. In one embodiment, thecomonomer is ethylene. These comonomers can be used in combinationsincluding lower and higher MW olefin components. Examples includepropylene/butene, hexene or octene copolymers, and ethylene/butene,hexene or octene copolymers, and propylene/ethylene/hexene-1terpolymers. Ethylene-propylene diene terpolymers and relatedelastomeric ethylene propylene copolymers may also be used. In anembodiment, the rubbery phase includes a block copolymer of propyleneand ethylene, with propylene as the major constituent and about 5 to 25wt % by weight ethylene. In this embodiment, the copolymer phase can bereferred to as an ethylene/propylene rubber. Small amounts of otherpolymerizable monomers may be included with the propylene and ethyleneif desired.

The matrix phase of the impact copolymer, typically a polypropylenehomopolymer, can include at least 40 wt %, optionally at least 50 wt %,or optionally at least 60 wt % by weight of the impact copolymer. In anembodiment, the matrix includes about 70 to 85 wt % by weight of theimpact copolymer. The rubbery phase can include about 7 to 22 wt %,optionally about 10 to 18 wt % by weight of the impact copolymer. Theoverall comonomer content, typically ethylene, of the total ICP can befrom about 1 to 30 wt %, optionally from about 3 to 15 wt %, oroptionally from about 5 to 10 wt % by weight of the total impactcopolymer.

In an embodiment, the ICP polypropylene may be selected from the groupof commercially available ICP polypropylenes. In another embodiment, theICP polypropylene is selected from the group sold under the productreference numbers 4280, 4320, 4520, 4720, 5571, 5720 and 5724 andcombinations thereof, all of which are commercially available from TotalPetrochemicals, Inc. Methods of making ICPs are well known in the art,for instance, in one non-limiting embodiment methods and techniques aredescribed in U.S. Pat. No. 6,657,024, incorporated herein by reference,may be used. Polypropylene ICPs have been found useful in certain ISBMapplications (see Patent Application No. 2009/0315226 to Fina, which isherein incorporated by reference).

The ICP may be one having a density range from 0.88 to 0.93 g/cm³,optionally from 0.89 to 0.92 g/cm³, and, optionally from 0.9 to 0.91g/cm³, as determined in accordance with ASTM D-1505. In an embodiment,the ICP may have a polydispersity from 4 to 12, optionally from 5 to 10.In an embodiment, the ICP may have xylene solubles of 25% or less. Inanother embodiment, the xylene solubles may range from 1 to 25 wt %,optionally 5 to 15 wt %. In an embodiment, the ICP may have a meltingpoint ranging from 155 to 170° C., optionally from 158 to 166° C.,optionally from 160 to 165° C. And in still another non-limitingembodiment the ethylene content of the ICP may range from 7 to 15 wt %,and optionally from 9 to 14 wt %.

The ICP polypropylene may have a melt flow rate (MFR) ranging from 0.1to 500 g/10 min, optionally from 1 to 250 g/10 min, optionally 1 to 100g/10 min, optionally 1 to 50 g/10 min, optionally from 1.0 to 20 g/10min, as determined in accordance with ASTM D-1238 condition “L.” The ICPcan have a weight average molecular weight Mw ranging from 280,000 to840,000, optionally ranging from 320,000 to 780,000, and optionallyranging from 420,000 to 700,000.

The impact copolymer can be made using any catalyst known in the art forpreparing an impact copolymer. Catalysts that can be used include, butare not limited to, metallocene catalyst systems, single site catalystsystems, Ziegler-Natta catalyst systems or combinations thereof. Thecatalysts may be activated for subsequent polymerization and may or maynot be associated with a support material. The homopolymer matrix andthe rubbery copolymer phase can be combined as a physical blend or anin-situ blend. In an in-situ blend, the rubber phase is incorporatedinto the homopolymer matrix by co-polymerization. The co-polymerizationprocess may include at least two stages, wherein the homopolymer isproduced in a first reaction zone, the product of which is transferredto a second reaction zone for contact with a comonomer and additionalmonomer (e.g, propylene) to produce a rubber component of theheterophasic copolymer. In an embodiment, the rubbery copolymer can beprepared using a controlled morphology catalyst that producesethylene-propylene copolymer spherical domains dispersed in asemi-crystalline polypropylene matrix. The equipment, processconditions, reactants, additives and other materials used inpolymerization processes will vary in a given process, depending on thedesired composition and properties of the polymer being formed. Suchprocesses may include solution phase, gas phase, slurry phase, bulkphase, high pressure processes or combinations thereof, for example.

Various other additives may be present in the impact copolymer, such as,for example, nucleating agents, clarifying agents, stabilization agents,antioxidants, anti-static agents, lubricants, filler materials, slipagents, acid neutralizers, and the like, or some combination thereof. Inan embodiment the additives are present in a quantity from 0.01 to 5 wt%, optionally from 0.1 to 3 wt %, optionally from 0.5 to 2 wt %, inrelation to the weight of the impact copolymer.

In one embodiment, the polypropylene copolymer is a random copolymer (orRCP). The random copolymer generally includes a single propylene phasewith a comonomer. The comonomer can be selected from C₂ to C₂₀ olefins.For example, the comonomer may be selected from ethylene, propylene,1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene,4-methyl- 1-pentene and combinations thereof. In one embodiment, therandom copolymer is a homopolymer of ethylene and propylene, withpropylene in the higher proportion. Propylene generally includes atleast 89 wt % of the random copolymer, while the olefin comonomer rangesfrom about 0.15 to 11 wt %, optionally from about 1 to 5 wt %, oroptionally from about 2 to 4 wt % based on the total weight of therandom copolymer. In an embodiment, the polypropylene is a randomethylene-propylene (C₂/C₃) copolymer and may range from 0.1 wt % to 10wt % ethylene, optionally from 2 wt % to 7 wt % ethylene, optionallyfrom 2 wt % to 6 wt % ethylene.

The random copolymer can be made using any catalyst known in the art formaking polypropylene polymer, such as metallocene catalyst systems,single site catalyst systems, Zieglet-Natta catalyst systems orcombinations thereof. In an embodiment, the olefin comonomer is randomlyinserted between the propylene groups; in one arrangement, there are noconsecutive sequences of such alpha olefin groups.

The RCP can have a melt flow rate from 0.5 to 500 g/10 min, optionallyfrom 0.5 to 250 g/10 min, optionally from 0.5 to 100 g/10 min,optionally from 1.0 to 50 g/10 min, optionally from 1.0 to 20 g/10 min,as determined in accordance with ASTM D-1238 condition “L.” In anembodiment, the RCP may have a density of from 0.890 g/cc to 0.920 g/cc,optionally from 0.895 g/cc to 0.915 g/cc, and optionally from 0.900 g/ccto 0.910 g/cc as determined in accordance with ASTM D-1505. The RCP canhave a molecular weight distribution from 2.5 to 20, optionally from 2.0to 10, optionally from 3.0 to 8. The xylene soluble fraction of therandom copolymer can be less than 10 wt %, or optionally between 5 and 8wt %. The RCP may have a melting point temperature of from 100° C. to165° C., optionally from 110° C. to 155° C., optionally from 128° C. to148° C.

The random copolymer may contain additives such as antioxidants, lightstabilizers, acid scavengers, lubricants, antistatic additives,nucleating/clarifying agents, colorants, or combinations thereof. In anembodiment the additives are present in a quantity from 0.01 to 5 wt %,optionally from 0.1 to 3 wt %, optionally from 0.5 to 2 wt %, inrelation to the weight of the random copolymer.

According to the present invention, the polypropylene copolymer, whichis either an impact copolymer or a random copolymer, is combined with ahard resin to form a polymer composition. The hard resin generallyprovides increased hardness to the polymer composition.

The polymer composition contains a hard resin in a quantity from 1 to 50wt %, optionally from 5 to 40 wt %, optionally from 10 to 30 wt %, inrelation to the weight of the polymer composition. The hard resin can bechosen from the group consisting of hydrocarbon resins, ketone resins,polyamide resins, colophonium, coumarone resins, terpene resins, orchlorinated aliphatic or aromatic hydrocarbon resins, or combinationsthereof.

The softening point of the hard resin as measured according ASTM E-28 isgenerally from 60° C. to 180° C., optionally from 80° C. to 150° C.,optionally from 100° C. to 140° C., optionally from 120° C. to 140° C.In general, the hydrocarbon resins have a number molecular weight Mnbetween 500 and 2500 (Mw 500 to 3000) and therefore differ fromlong-chain high molecular weight polymers, whose Mw (weight mean) isgenerally in the magnitude of 10,000 to multiples of 100,000. In anon-limiting embodiment the hard resin can have a melt flow rate (MFR)of from 1 to 50 g/10 min at 230° C., 2.16 Kg. Optionally the MFR canrange from 10 to 40 g/10 min, optionally from 20 to 30 g/10 min.

In an embodiment the hydrocarbon resins are hydrogenated petroleumresins. These are usually prepared by catalytically hydrogenating athermally polymerized steam cracked petroleum distillate fraction,especially a fraction having a boiling point of between 20° C. and 280°C. These fractions usually are of compounds having one or moreunsaturated cyclic rings in the molecule, such as cyclodienes,cycloalkenes and indenes. It is also possible to hydrogenate resinsproduced by the catalytic polymerization of unsaturated hydrocarbons.

The petroleum resins are those hydrocarbon resins that are manufacturedthrough polymerization of petroleum materials in the presence of acatalyst. These petroleum materials typically contain a mixture ofresin-producing substances such as styrene, methylstyrene, vinyltoluene, indene, methyl indene, butadiene, isoprene, piperylene, andpentylene. The styrene resins are homopolymers of styrene or copolymersof styrene with other monomers such as methylstyrene, vinyl toluene, andbutadiene. The cyclopentadiene resins are cyclopentadiene homopolymersor cyclopentadiene copolymers, which can be obtained from coal tardistillates and decomposed petroleum gas. These resins can bemanufactured by keeping the materials that contain cyclopentadiene athigh temperature for a long time. Dimers, trimers, or oligomers may beobtained as a function of the reaction temperature.

The terpene resins are polymers of terpenes, i.e., hydrocarbons of theformula C₁₀H₁₆, which are contained in almost all ethereal oils or oilyresins of plants, and phenol-modified terpene resins. Pinene, α-pinene,dipentene, limonene, myrcene, camphene, and similar terpenes areexamples of terpenes. The hydrocarbon resins may also be modifiedhydrocarbon resins. The modification is generally performed throughreaction of the raw materials before polymerization, by introducingspecial monomers, or through reaction of the polymerized product,hydrogenation or partial hydrogenation particularly being performed.

The hard resin can be from 1 to 50 wt %, optionally 5 to 40 wt %,optionally 5 to 30 wt %, of the polymer composition. The hard resin maybe incorporated into the polymer composition by various ways. It can beprovided as a final pellet, where the polypropylene and hard resin havebeen extruded together to form an intimate melt blend, then pelletized.It can be provided as a pellet masterbatch, which is co-blended withneat polypropylene pellets at a preform injection molder. It can also beprovided in a natural form, where neat polypropylene and neat hard resinare mixed at a preform injection molder. Generally it is desired to havean intimate melt blend that has been cooled and pelletized to obtainenhanced consistency of the final product.

The polymer composition can be used in various applications including,but not limited to, by injection molding, rotomolding, blow molding orextrusion such as cast or oriented film, sheet or profile, andthermoforming. In one embodiment, the application of the polymercomposition is injection stretch blow molding (ISBM).

The polymer composition can be used to make various articles including,but not limited to, food containers, health care products, durablehousehold and office goods, squeeze bottles, clear flexible film andsheet, automotive interior trim and fascia, wire, cable, pipe, and toys.In one embodiment, the polymer composition can be used to make articlesused in low temperature packaging applications, such as lids orcontainers, including low temperature storage containers.

In one embodiment, the present invention is a polymer composition havinga polypropylene impact copolymer component and 1 to 50 wt % of a hardresin component. The composition can have top load strength from about130 to 160 N, can have at least a 90% pass rate for a drop impact test(from 6 feet at 40° F.), haze from about 60 to 80%, and gloss)(45° fromabout 5 to 15. A normalized top load strength calculated by the top loadstrength divided by bottle weight can range from about 5.0 to 10.0 N/g.In an embodiment the normalized top load strength is at least 5.3 N/g,optionally at least 5.5 N/g, optionally at least 6.0 N/g.

In one embodiment, the present invention is a polymer composition of apolypropylene random copolymer and from 1 to 50% by weight hard resin.The composition can have top load strength from about 200 to 350 N, a 0to 50% pass rate for a drop impact test (from 6 feet at 40° F.), hazefrom about 1 to 5%, and gloss)(45° from about 60 to 90. A normalized topload strength calculated by the top load strength divided by bottleweight can range from about 6.5 to 15.0 N/g. In an embodiment thenormalized top load strength is at least 7.0 N/g, optionally at least8.0 N/g, optionally at least 9.0 N/g.

In one embodiment, the present invention is a method for making apolymer composition, including the steps of polymerizing a polypropylenecopolymer and combining the resultant product with a hard resin to get aproduct having 1 to 50 wt % hard resin, where the polypropylenecopolymer is either a random copolymer or and impact copolymer.

In one embodiment, the present invention is a method for making aninjection stretch blow molded article, using a polymer composition thatincludes a polypropylene copolymer and 1 to 50 wt % of a hard resin,where the polypropylene copolymer is either a random copolymer or animpact copolymer, or a combination thereof.

In one embodiment, the present invention is an ISBM article having apolymer composition of a polypropylene copolymer and 1 to 50 wt % of ahard resin, where the polypropylene copolymer is either a randomcopolymer or an impact copolymer, or a combination thereof. In anembodiment, the ISBM article is used in low temperature applications. Inan embodiment, the ISBM article is an opaque container that shieldslight from the contents of the container.

In an embodiment the addition of the hard resin improves the barrierproperties of a polymer composition as compared to a polymer compositionmade from a substantially similar polymer composition without the hardresin. In an embodiment the water vapor transmission rate (WVTR) isreduced by the addition of the hard resin. In an embodiment the WVTR isreduced by at least 10%, optionally by at least 5%, with the addition ofthe hard resin. In an embodiment the oxygen transmission rate (O₂TR) isreduced by the addition of the hard resin. In an embodiment the O₂TR isreduced by at least 10%, optionally by at least 5%, with the addition ofthe hard resin.

The following examples are meant to be merely illustrative of particularembodiments of the present invention, and are by no means limiting ofthe scope of the invention.

EXAMPLE 1

A polymer composition including a polypropylene impact copolymer and ahard resin was prepared and tested for top load strength, drop impactstrength, gloss, and haze. The polymer composition contained acommercial polypropylene impact copolymer (ICP), sold by TotalPetrochemicals as 5946WZ, and a commercial hard resin masterbatch (50/50blend of hard resin and PP), PA609A, from Exxon Mobil that is ahydrogenated polyterpene having a MFR ranging from 10 to 30 g/10 min at230° C., 2.16 Kg. The hard resin masterbatch was 20% by weight of thecomposition.

The ICP and hard resin were dry blended and subsequently injectionmolded into 23 g preforms on a Netsal injection molder under thefollowing injection molding conditions: 23 g preform weight, F finish,250° C. barrel temperature, 250° C. hot runner temperature, 50/50° F.mold temperature (static/move), 5 mm/s injection speed, 15 sec coolingtime, 4 sec hold time, and a 29 second cycle time. The preforms wereconditioned at room temperature for at least 24 hours before they werestretch-blow-molded into 500 mL bottles on an ADS G62 linear injectionstretch blow molder. Neat ICP preforms were also molded under similarconditions and stretch-blow-molded into bottles for comparison ofmechanical and optical properties. Table 1 shows the comparativeproperties.

TABLE 1 Properties of bottles prepared from ICP and ICP/20% Hard Resin.ICP ICP + 20 wt % Hard Resin Top load (N) 118 146 Gloss, 45° 10.9 10.1Haze (%) 76.5 75.8 Drop impact, Vertical: 12 of 12 pass Vertical: 12 of12 pass 6 feet @ 40° F. Horizontal: 12 of 12 pass Horizontal: 12 of 12pass

As shown in Table 1, with an incorporation of 20% hard resin, the bottletop load strength was improved by about 24%, while the drop impactstrength remained high enough to pass the typical industrial standardfor low temperature packaging applications. A normalized top loadstrength calculated by the top load strength divided by bottle weightimproved from about 5.1 N/g to greater than 6.0 N/g. Optical propertieswere virtually unaltered by the addition of the hard resin.

EXAMPLE 2

Polymer compositions of polypropylene random copolymer and varyingamounts of hard resin were prepared and tested for top load strength,drop impact strength, gloss and haze. The polymer compositions containeda commercial polypropylene random copolymer (RCP), sold by TotalPetrochemicals as 7525M2, and a commercial hard resin masterbatch (50/50blend of hard resin and PP), PA609A, from Exxon Mobil. Four compositionswere prepared, containing 0, 10, 20, and 40% by weight PA609A of thetotal polymer composition.

The RCP and hard resin masterbatch were dry blended and subsequentlyinjection molded into 23 g preforms on a Netsal injection molder underthe following injection molding conditions: 23 g preform weight, Ffinish, 250° C. barrel temperature, 250° C. hot runner temperature,50/50° F. mold temperature (static/move), 5 mm/s injection speed, 15 seccooling time, 4 sec hold time, and a 29 second cycle time. The preformswere conditioned at room temperature for at least 24 hours before theywere stretch-blow-molded into bottles on an ADS G62 linear injectionstretch blow molder. Neat RCP preforms were also molded under similarconditions and stretch-blow-molded into bottles for comparison.Generally, the addition of a hard resin had little effect on the preforminjection molding process.

The neat RCP and the blend preforms were successfully blow molded into500 mL bottles. A 100% good bottle rate was achieved at both 2000 and3000 b/h, the molded bottles exhibiting uniform appearance and highclarity. The bottles were subsequently tested for top load, drop impact,haze, and gloss.

The top load strength test showed that the incorporation of hard resincould effectively improve the stiffness of the molded bottles. Table 2and FIG. 1 show the top load strength in N for bottles made from thefour polymer compositions. The addition of 20% and 40% of PA609Aimproved top load strength by about 52% and 94%, respectively. Anormalized top load strength calculated by the top load strength dividedby bottle weight was 6.3 N/g for the composition with no hard resinadded. The addition of 10% PA609A resulted in an increase in normalizedtop load strength to 6.8 N/g. The addition of 20% PA609A resulted in anincrease to 9.5 N/g. The addition of 40% PA609A resulted in an increasein normalized top load strength to 12.0 N/g.

Drop impact test results showed that the addition of hard resindecreased the impact strength of the molded bottles, as shown in Table2.

TABLE 2 Drop Impact Strength of Polypropylene Random Copolymer/HardResin Compositions. RCP + 10% RCP + 20% RCP + 40% RCP PA609A PA609APA609A Top load (N) 145 156 219 275 Gloss, 45° 82 68 76 75 Haze (%) 1.11.7 2.6 1.8 Drop Impact 4 feet @ 40° F. Vertical 3 of 12 fail 12 of 12fail 12 of 12 fail 12 of 12 fail Horizontal 0 of 12 fail 0 of 12 fail 12of 12 fail 12 of 12 fail

The bottles became more brittle with the addition of the hard resin.When the concentration of hard resin was above 20%, the bottles were sobrittle that they shattered during the drop impact testing. Thus, thepolymer compositions of polypropylene random copolymer and hard resincan be used most effectively in the fields where drop impact performanceis not critical.

The incorporation of hard resin only led to slight changes in bottleoptical properties. FIG. 2 is a chart showing gloss)(45° for bottlesmade from the four polymer compositions. FIG. 3 is a chart showing haze(%) for bottles made from the four polymer compositions. These chartsshow that addition of hard resin decreases gloss slightly and increaseshaze slightly, but the values are not significantly different from neatRCP bottles.

Drop impact strength provides information about the strength of an ISBMend-use article when dropped from a height. Tests of the drop impactstrength may be carried out by dropping a set number of filled andcapped bottles (e.g., 12) vertically onto the bottle base andhorizontally onto the bottle side. The weight and the volume of thebottles may include any suitable weight and volume. In an embodiment,the bottle has a weight of 23 g and a volume of 500 mL.

Testing of the drop impact strength may include dropping bottles, whichhave been stored at 40° F. or at room temperature for at least 12 hoursfrom 4 or 6 feet (ft). A material is considered to have passed the dropimpact strength test if all articles in the set (i.e., 12) were stillintact after initial impact and there was zero failure. The failurecriteria may include: a) any breakage of any location (including crackedbase, broken finish), zero is acceptable; b) delamination of any sizeand location; c) denting of any size and location. Typically, theexperiment may be repeated if the lid on the bottle, instead of thebottle itself, failed.

Top load strength and bumper compression strength provide informationabout the crushing properties of an ISBM end-use article when employedunder crush test conditions. Tests of the top load and bumpercompression strength may be carried out by placing the ISBM article on alower plate (vertically for top load strength and horizontally forbumper compression) and slowly raising it against an upper plate tomeasure the corresponding load capacity of the ISBM articles (maximumvalue for top load strength and the value at ½ inch deflection forbumper compression strength).

As used herein, “cold temperature” refers to a range of temperaturestypical of standard refrigeration methods and means that a temperaturedifference of a few degrees does not matter to the phenomenon underinvestigation, such as drop impact testing. In some environments, coldtemperature may include a temperature of from about 0° C. to about 10°C. (32° F. to 50° F.), while in other environments, cold temperature mayinclude a temperature of from about 2° C. to about 8° C. (35.6° F. to46.4° F.), for example. For purposes of cold temperature drop impacttesting, as discussed herein, it is customary in the industry to test ata temperature of about 4° C. (39.2° F.). However, cold temperaturemeasurements generally do not include close monitoring of thetemperature of the process and therefore such a recitation does notintend to bind the embodiments described herein to any predeterminedtemperature range.

As used herein, “opaque” means an article is impenetrable to visiblelight, that is, an opaque object prevents transmission of essentiallyall visible light. “Transparent” means essentially all visible lightpasses through the article. The term “semi-opaque” means some, but notall, visible light passes through the article.

As used herein, the term “polymer composition” refers to a blend of twoor more polymers, and is interchangeable with the term “polymer blend”.In the present invention, the polymer compositions are blends of a hardresin and another polypropylene polymer.

The term “impact copolymer” refers to a polymer containing a matrixphase that provides stiffness and a dispersed rubbery phase thatprovides toughness and impact absorption.

The term “random copolymer” refers to a polymer containing a comonomerthat is randomly distributed.

It is to be understood that while illustrative embodiments have beendepicted and described, modifications thereof can be made by one skilledin the art without departing from the spirit and scope of thedisclosure. Where numerical ranges or limitations are expressly stated,such express ranges or limitations should be understood to includeiterative ranges or limitations of like magnitude falling within theexpressly stated ranges or limitations (e.g., from about 1 to about 10includes, 2, 3, 4, etc.; greater than 0.10 includes 0.11, 0.12, 0.13,etc.).

Use of the term “optionally” with respect to any element of a claim isintended to mean that the subject element is required, or alternatively,is not required. Both alternatives are intended to be within the scopeof the claim. Use of broader terms such as comprises, includes, having,etc. should be understood to provide support for narrower terms such asconsisting of, consisting essentially of, comprised substantially of,etc.

Depending on the context, all references herein to the “invention” mayin some cases refer to certain specific embodiments only. In other casesit may refer to subject matter recited in one or more, but notnecessarily all, of the claims. While the foregoing is directed toembodiments, versions and examples of the present invention, which areincluded to enable a person of ordinary skill in the art to make and usethe inventions when the information in this patent is combined withavailable information and technology, the inventions are not limited toonly these particular embodiments, versions and examples. Also, it iswithin the scope of this disclosure that the aspects and embodimentsdisclosed herein are usable and combinable with every other embodimentand/or aspect disclosed herein, and consequently, this disclosure isenabling for any and all combinations of the embodiments and/or aspectsdisclosed herein. Other and further embodiments, versions and examplesof the invention may be devised without departing from the basic scopethereof and the scope thereof is determined by the claims that follow.

What is claimed is:
 1. A method of making a polymer compositioncomprising: blending a polypropylene impact copolymer including a matrixphase and a rubbery phase dispersed within the matrix phase with a hardresin to form the polymer composition, wherein the hard resin has asoftening point, as measured according ASTM E-28, of from 60° C. to 180°C. and a melt flow rate (MFR) of from 1 to 50 g/10 min at 230° C.,wherein the hard resin is selected from the group consisting of ketoneresins, polyamide resins, colophonium, coumarone resins, terpene resins,or chlorinated aliphatic or aromatic hydrocarbon resins, andcombinations thereof; and extruding the polymer composition to form asubstantially homogenous polymer blend, wherein the polymer blendcontains 1 to 50% by weight of hard resin.
 2. The method of claim 1,wherein the polypropylene impact copolymer is an impact copolymercomprising a polypropylene homopolymer and an ethylene-propylene rubber.3. The method of claim 2, wherein the homopolymer comprises at least 60%by weight of the impact copolymer, and the ethylene-propylene rubbercomprises less than 40% by weight of the impact copolymer.
 4. The methodof claim 2, wherein the impact copolymer has a melt flow rate from 1 to500 g/10 min.
 5. The method of claim 1, wherein the polypropylenecopolymer is a random copolymer.
 6. The method of claim 5, wherein therandom copolymer contains less than 10% by weight of an ethylenecomonomer.
 7. The method of claim 1, wherein the polymer composition isused to make an injection stretch blow molded article.
 8. A method ofmaking an article comprising: providing a polymer composition comprisinga polypropylene impact copolymer including a matrix phase and a rubberyphase dispersed within the matrix phase and 1 to 50% by weight of hardresin, wherein the hard resin has a softening point, as measuredaccording ASTM E-28, of from 60° C. to 180° C. and a melt flow rate(MFR) of from 1 to 50 g/10 min at 230° C., wherein the hard resin isselected from the group consisting of ketone resins, polyamide resins,colophonium, coumarone resins, terpene resins, or chlorinated aliphaticor aromatic hydrocarbon resins, and combinations thereof; injectionmolding polymer composition into a preform; and stretch-blowing thepreform into an article.
 9. The method of claim 8, wherein the articleis a container used in cold temperature applications of less than 40° F.